package/pcm-tools: fix static build

Don't build c_example which needs a dynamic library and so will raise
the following static build failure since bump to version 2021.10 in
commit d1d93d488c76d4bc2551270007096693d8194435 and
https://github.com/opcm/pcm/commit/12647a6ee579c29bd306fd034470eb62dcb3156e:

/home/buildroot/autobuild/instance-2/output-1/host/opt/ext-toolchain/bin/../lib/gcc/i686-buildroot-linux-uclibc/9.3.0/../../../../i686-buildroot-linux-uclibc/bin/ld: cannot find -lpcm

Fixes:
 - http://autobuild.buildroot.org/results/1276a3d49c8848039f034e7f03632df365097e94

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pcm-tools/pcm-tools.mk

@@ -17,7 +17,8 @@ define PCM_TOOLS_BUILD_CMDS
 	touch $(@D)/daemon-binaries
 	$(TARGET_MAKE_ENV) $(MAKE) $(TARGET_CONFIGURE_OPTS) -C $(@D) \
 		CXXFLAGS="$(TARGET_CXXFLAGS) -std=c++11 -fPIC" \
-		UNAME=Linux HOST=_LINUX
+		UNAME=Linux HOST=_LINUX \
+		$(foreach f,$(PCM_TOOLS_EXE_FILES),$(f).x)
 endef
 
 ifeq ($(BR2_PACKAGE_PCM_TOOLS_PMU_QUERY),y)